Steam flooding is a common method for producing oil from reservoirs that would otherwise be difficult to produce from using conventional resources. This type of enhanced oil recovery (EOR) technique typically utilizes a plurality of steam injection wells interspersed with production wells. See, e.g., Hutchison et al., U.S. Pat. No. 4,099,563, issued Jul. 11, 1978; and Shu, U.S. Pat. No. 4,431,056, issued Feb. 14, 1984.
Steam injection wells are often partially cased down close to the region in which steam is to be injected. The region of the well where steam is to be injected, however, must remain open to the formation comprising the target reservoir. In this region, a liner string is typically run some distance (e.g., several hundred to several thousand meters), with slots, holes, or other porous channels permitting fluid communication with the formation along at least portions of the length of liner string. See, e.g., Themig, U.S. Pat. No. 4,942,925, issued Jul. 24, 1990.
Ideally, during steam injection, an even flux of fluid to the reservoir is maintained. In practice, however, unrestricted flow in the annulus, complicated by reservoir heterogeneities and/or varying reservoir pressures, results in an uneven flow of fluid to the reservoir. In turn, this uneven flux or flow of fluid to the formation reduces overall hydrocarbon extraction yields from the reservoir.
A number of devices are currently employed in the industry to ensure a fairly even flux of fluid out of the liner and into the formation. Such devices generally induce an annular obstruction (i.e., a barrier) within the annular region (see, e.g., Grigsby et al., U.S. Pat. No. 6,564,870, issued May 20, 2003). In some instances, such devices are actively deployed such that specific actions are taken to actuate and/or activate the obstruction (e.g., hydraulic and/or mechanical actuation). The downside to such devices, and their method of deployment, is the need to run mechanical and/or hydraulic actuation means downhole.
In other instances, the activation of such above-mentioned devices is passive—requiring no direct external intervention, e.g., a “swell packer” that comprises a mandrel wrapped in an elastomeric material, wherein the elastomeric material swells in the presence of a particular fluid that is introduced into the annular region.
In view of the foregoing, an improved method and/or system for passively obstructing the annular region (or a passive obstruction comprising active elements, e.g., a hybrid obstruction) in a steam injection well would be extremely useful—particularly wherein such a method and/or system provides better control over the actuation process without having to run tools or devices downhole to mechanically and/or hydraulically actuate an annular obstruction packer.